Part of the great thing about quilters is that they generally tend to be an honest group of people and with that comes an honor code of sorts.
If someone is unhappy with a block or a classified item we as adults should be able to work it out amongst ourselves without publicizing to other quilters.
My opinion on a rating system for whatever it is worth is this:
Everyone's opinion here of "quality" fabric or "quality" work may be different and sometimes is even based on economical factors. Everybody started somewhere and has learned along the way what good workmanship and good quality fabric was with help and guidance from others. I feel if we institute a feedback system someone who is new to the quilting world may become discouraged if they send a block that isn't up to someone else's standards and that would be hurtful.
The best way to help people grow is to explain to them why something could be better not rate them on it.
This is just my two cents...
Hugs
April